When outer bark is carefully scraped to reveal inner bark tissue, small cankers are observed on branches. Once coalescing of cankers occurs, large, dead (cankered) areas can be found on branches and main stem

Numerous, meandering tunnels and galleries of the walnut twig beetle may be observed in the bark

Both the fungal cankers and the walnut twig beetle are found in the bark down to the cambial region (not into the wood)